Described herein is a new and distinctive switchgrass variety, designated EG1102. This variety is also known by the breeder identifier NFSG-992.
Switchgrass is a warm season perennial grass and is one of the dominant species of the central North American tallgrass prairie. Switchgrass can be found in remnant prairies, along roadsides, pastures and as an ornamental plant in gardens. Other common names for this grass include tall panic grass, Wobsqua grass, lowland switchgrass, blackbent, tall prairiegrass, wild redtop and thatchgrass. Switchgrass is a hardy, perennial rhizomatous grass which begins growth in late spring. It is typically shorter than Big Bluestem grass or Indiangrass. Switchgrass is used as pasture forage plant, as ground cover to control erosion and as a livestock feed.
Switchgrass uses C4 carbon fixation, giving it an advantage in conditions of drought and high temperature. The deep roots of switchgrass advantageously sequester large amounts of carbon (McLaughlin and Kszos, 2005 “Development of switchgrass (Panicum virgatum) as a bioenergy feedstock in the United States.” Biomass Bioenergy 28:515-535). Once established switchgrass is also tolerant of flooding and grows rapidly, capturing a significant amount of solar energy and turning it into stored energy in the form of lignocellulosic components.
Switchgrass is often considered a good candidate for biofuel, especially ethanol fuel, production due to its hardiness against soil and climate conditions, rapid growth and low fertilization and herbicide requirements. Switchgrass offers important advantages as an energy crop, in part because it can be liquified, gasified, or burned directly. Ethanol production from switchgrass can provide as much as twenty times more net energy output than corn and removes considerably more CO2 from the air.
Combustion of switchgrass pellets can result in only 3% to 4% of original mass remaining as ash due in part to switchgrass' lower silica and chloride content as compared to cool season grasses. Ash contents can be further reduced by allowing switchgrass to overwinter in the field, thereby reducing the silica and chloride contents further through the process of leaching.
Despite the many advantages that switchgrass has as a crop for food, feed or energy, in order for this grass to fulfill its promise, new varieties of switchgrass are needed. For the most part, existing varieties do not differ from the wild populations from which they are derived. What intentional breeding has occurred has focused on improving switchgrass as a forage plant, i.e., palatability and nutrition. The goal of plant breeders is to combine in a single variety an improved combination of desirable traits from the parental germplasm.
Choice of breeding or selection methods depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., F1 hybrid cultivar, pureline cultivar, etc.). Popular selection methods commonly include population formation by hybridization, genomic selection, marker assisted selection, recurrent selection, mutation breeding, single-seed descent, bulk selection, pedigree selection, modified pedigree selection, and mass selection.
The complexity of inheritance influences choice of the breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes.
Each breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful cultivars produced per unit of input (e.g., per year, per dollar expended, etc.).
Promising advanced breeding lines are tested and compared to appropriate standards in environments representative of the commercial target area(s) for one or more years. The best lines are candidates for new commercial cultivars; those still deficient in a few traits may be used as parents to produce new populations for further selection.
These processes, which lead to the final step of marketing and distribution, usually take years from the time the first cross or selection is made. Therefore, development of new cultivars is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.
A most difficult task is the identification of individuals that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar.
The goal of switchgrass plant breeding is to develop new switchgrass cultivars and hybrids. The breeder initially selects and/or crosses two or more parental lines, followed by repeated population selection, producing many new genetic combinations. The breeder can theoretically generate billions of different genetic combinations via crossing and mutations.
Each year, the plant breeder selects the germplasm to advance to the next generation during the process of development of a new cultivated variety. This germplasm is grown under unique and different geographical, climatic and soil conditions and further selections are then made during and at the end of the growing season. The cultivars that are developed are unpredictable because the breeder's selection occurs in unique environments with no control at the DNA level (using conventional breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting lines he develops, except possibly in a very gross and general fashion. This unpredictability results in the expenditure of large amounts of research monies to develop superior new switchgrass cultivars.
The development of new switchgrass cultivars requires the development and selection of switchgrass varieties, the crossing of these varieties and selection of superior lines. Additional data on parental lines, as well as the phenotype of the hybrid, influence the breeder's decision whether to continue using specific parents in a breeding program.
Mass and recurrent selections can be used to improve populations of either self- or cross-pollinating crops. A genetically variable population of heterozygous individuals is either identified, or created, by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued.
Backcross breeding has been used to transfer genes for a simply inherited, highly heritable trait into a desirable homozygous cultivar or inbred line which is the recurrent parent. The source of the trait to be transferred is called the donor parent. After the initial cross, individuals possessing the phenotype of the donor parent are selected and repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent.
The single-seed descent procedure in the strict sense refers to planting a segregating population, harvesting a sample of one seed per plant, and using the one-seed sample to plant the next generation. When the population has been advanced from the F2 to the desired level of inbreeding, the plants from which lines are derived will each trace to different F2 individuals. The number of plants in a population declines each generation due to failure of some seeds to germinate or some plants to produce at least one seed. As a result, not all of the F2 plants originally sampled in the population will be represented by a progeny when generation advance is completed.
In a multiple-seed procedure, switchgrass breeders commonly harvest one or more inflorescence from each plant in a population and thresh them together to form a bulk. Part of the bulk is used to plant the next generation and part is put in reserve. The procedure has been referred to as modified single-seed descent or the inflorescence-bulk technique.
In addition to phenotypic observations, the genotype of a plant can also be examined. There are many laboratory-based techniques available for the analysis, comparison and characterization of plant genotype; among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length polymorphisms (AFLPs), Simple Sequence Repeats (SSRs—which are also referred to as Microsatellites), and Single Nucleotide Polymorphisms (SNPs). Molecular markers can be used in marker assisted breeding for one or more traits, for genomic selection, or to generate a chromosome map that can be used in breeding to identify quantitative trait loci or map particular genes.
Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor and consumer for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.
Switchgrass is an important and valuable crop. Thus, an important and ongoing goal of switchgrass plant breeders is to develop stable, high biomass yielding, biofuel conversion efficient cultivars that are agronomically sound. To accomplish this goal, the switchgrass breeder must select and develop switchgrass plants that have traits that result in new cultivars.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.